1. Field of the Invention
This invention relates generally to extensible and retractable members and, specifically, to such members and a method of forming the same for use as rigid supports, as in the case of aerial masts and antennae.
Many types of extensible and collapsible members are known, such as antennae used in communication, support platforms used in harvesting fruit, brooms used in inspecting and servicing machinery, elevators for fire hoses, and the like.
The typical prior art device utilized a telescoping action which resulted in several inherent problems. These problems included the length of span and span strength, the support or reinforcement provided by adjacent spans, and the number of spans needed to effect a desired amount of extension.
There exists a need, therefore, for an extensible and collapsible member which is strong and rigid when extended and which is free from the problems associated with the prior art devices.
There exists a need for such an extensible and retractable member which is extended by orienting and successively uniting similar flexible strips of material which can be retracted by successively disassembling the same strips.
Another need which is met by the present invention is the provision of an extensible mast or antenna which is erectable from a portable base and which has a very small volume or bulk when retracted for ease of transport.
2. Summary of the Invention
The extensible member of the invention includes a plurality of tape reels mounted upon a base which are angularly oriented thereon with respect to a common, vertical axis. Each of the tape reels is adapted to receive a resilient metal tape having longitudinal edges, for winding and unwinding the tape. Guide means located on the base receive the respective longitudinal edges of the metal tapes and orient the tape, whereby the tapes are fed upwardly in planes parallel to the vertical axis and at an angle to each other to form a rigid structure.
Winding means on the base dispense a reinforcing winding simultaneously with the upward movement of the tapes for strengthening the rigid structure. Preferably, the winding means include a bevel gear driven by a main drive. The bevel gear has a ring gear mounted thereon which is driven by the bevel gear for rotation about the vertical axis. The ring gear carries a plurality of rotatable windings thereon. Each of the rotatable windings has a planetary gear surface for contacting the mating surface of a stationary sun gear mounted on the base. Movement of the main drive and, in turn, the bevel gear causes the winding to rotate about the vertical axis as the rigid structure is being erected to wrap the structure with a reinforcing winding.
Additional objects, features and advantages will be apparent in the written description which follows.